Scrumhalf Mike Petri crossed for a first-half try and Chris Wyles kicked a conversion and two penalty goals in a physical match against the Russian Bears, who had to wait until seven days into the tournament to play in their first ever match at the World Cup.
Yury Kushnarev kicked a penalty goal in the third minute to score Russia's first points, but the Americans rallied to take a 10-3 halftime lead. Heavy rain drenched the crowd of nearly 14,000 at Taranaki Stadium in the second half, restricting scoring to one penalty goal apiece.
Wyles was outstanding, making light of the slippery conditions by completing some excellent takes from high balls hoisted by Russia. While locks Hayden Smith and John van der Giessen were instrumental in the U.S. stealing six of the Bears' lineout throws, often at crucial times.
"It's an awesome feeling," U.S. captain Todd Clever said. "I'm proud of the boys for sticking through.
"We made it tough for ourselves but the crowd helped get us through that one."
The Americans started the tournament with an encouraging performance in a 22-10 loss to Ireland here on Sept. 11 and now have a long-awaited win, but the competition becomes more intense in the next match, against two-time champion Australia on Sept. 23.
The Eagles beat Japan at the 1987 and 2003 World Cups, their only wins in five previous tournaments, so there was plenty of jubilation.
Clever said he was nervous in the closing stages, desperate to hang on and end a streak of six consecutive losses at the World Cup.
"They're a tough team and they're improving. Every time we play them, they're getting better and better," he said of the Russians. "I'm just proud of the guys that we were able to finish through that."
The Americans started on the back foot when Petri had a kick charged down in the opening minute and the Russians went immediately on the attack. But several attacking raids only resulted in three points from the penalty.
Petri made up for his error when he finished off a long-range try in the 18th minute, sliding over beside the posts.
Wyles converted but then there was 45 minutes without a point in the match before Wyles extended the lead to 13-3 with his penalty in the 64th minute.
Konstantin Rachkov landed a penalty goal in the 77th minute to bring the Russians within a converted try after a sustained period of pressure, but the Americans held firm for the last three minutes to ensure the win. Russia picked up a bonus point for losing by a margin of fewer than seven.
"We tried to show our best, it's our first game," Russia's Alexander Voytov said. "We were trying to prepare for this game as much as possible. It was a tough game -- it was unlucky with the loss but we will try to show our good game the next games."
United States 13 (Mike Petri try; Chris Wyles 2 penalties, conversion) def. Russia 6 (Yury Kushnarev, Konstantin Rachkov penalties). HT: 10-3.